Our new unit is chemical equilibrium. To explore this topic before being officially introduced to it, we used the simulation and a few POGILs. I think that this is a good way of being introduced to something new, as it helps you get familiar with the topics by introducing similar things and starting off very basic. To reflect on these pogils I thought they were very useful in helping me get a good head start on the topic of equilibrium. Basically equilibrium is based on a major concept:
A reaction can go both ways - the forward and the reverse reactions.
At equilibrium, the overall rates at which the forward and reverse reactions occur are equal. Once equilibrium is reached, the concentration of the reactants and the products doesn't change because the rates are equal:
The most important concept in equilibrium is the equilibrium constant. The equilibrium constant, Keq, is the concentration or the partial pressure of the products, raised to their stoichiometric coefficients, divided by the concentration/partial pressure of the reactants, raised to their stoichiometric coefficients. If this number is less than one, there are more reactants than products at equilibrium. If this number is greater than one, there are more products at equilibrium.
The second important concept is Le Chatelier's Principle. This states that if a system at equilibrium is disturbed, the reaction will shift in order to go back to equilibrium. There are three such disturbances:
1. Changing the concentration of a reactant/product: If we add more reactant, the reaction will shift to the right, in order to make more products, and vice versa. In this instance, Keq does not change because the ratio of concentrations is preserved.
2. Changing the volume of the vessel: If we decrease the volume, the pressure will increase, so the reaction will shift to the side with less moles in order to lower the pressure back to the original, and vice versa. Again, in this case, Keq does not change.
3. Changing the temperature: This is the only way to change the equilibrium constant. If reaction is endothermic, and we increase the temperature, more products will be made, and Keq will increase, and vice versa.
To reflect on this, I think this principle is essential to equilibrium as a whole and I definitely need to understand it more. I came after school a couple of times to work on the equilibrium worksheets and I think I have a very good understanding of how to do most of the calculations in this unit. Rice tables are very easy for me now and I think that is a big part of this unit.
Adding a catalyst to the reaction will not change anything except the rate of the reaction. It will, however, change increase BOTH the forward and reverse reaction, making the reaction achieve equilibirium faster.
It is important to remember that solids and liquids do not play a role in the calculation of the equilibrium constant. Their concentration or partial pressure is always constant, and since Keq is a ratio, they end up cancel out.
The last concept we learned was the relationship between thermodynamics and equilibrium. This was confusing at first, but now I understand it better, although I don't know how to answer some of the questions on the Equilibrium III worksheet. There is a relationship between Gibbs Free Energy and the equilibrium constant:
ΔG0=−RTlnK
ΔG0
A reaction can go both ways - the forward and the reverse reactions.
At equilibrium, the overall rates at which the forward and reverse reactions occur are equal. Once equilibrium is reached, the concentration of the reactants and the products doesn't change because the rates are equal:
The most important concept in equilibrium is the equilibrium constant. The equilibrium constant, Keq, is the concentration or the partial pressure of the products, raised to their stoichiometric coefficients, divided by the concentration/partial pressure of the reactants, raised to their stoichiometric coefficients. If this number is less than one, there are more reactants than products at equilibrium. If this number is greater than one, there are more products at equilibrium.
The second important concept is Le Chatelier's Principle. This states that if a system at equilibrium is disturbed, the reaction will shift in order to go back to equilibrium. There are three such disturbances:
1. Changing the concentration of a reactant/product: If we add more reactant, the reaction will shift to the right, in order to make more products, and vice versa. In this instance, Keq does not change because the ratio of concentrations is preserved.
2. Changing the volume of the vessel: If we decrease the volume, the pressure will increase, so the reaction will shift to the side with less moles in order to lower the pressure back to the original, and vice versa. Again, in this case, Keq does not change.
3. Changing the temperature: This is the only way to change the equilibrium constant. If reaction is endothermic, and we increase the temperature, more products will be made, and Keq will increase, and vice versa.
To reflect on this, I think this principle is essential to equilibrium as a whole and I definitely need to understand it more. I came after school a couple of times to work on the equilibrium worksheets and I think I have a very good understanding of how to do most of the calculations in this unit. Rice tables are very easy for me now and I think that is a big part of this unit.
Adding a catalyst to the reaction will not change anything except the rate of the reaction. It will, however, change increase BOTH the forward and reverse reaction, making the reaction achieve equilibirium faster.
It is important to remember that solids and liquids do not play a role in the calculation of the equilibrium constant. Their concentration or partial pressure is always constant, and since Keq is a ratio, they end up cancel out.
The last concept we learned was the relationship between thermodynamics and equilibrium. This was confusing at first, but now I understand it better, although I don't know how to answer some of the questions on the Equilibrium III worksheet. There is a relationship between Gibbs Free Energy and the equilibrium constant:
To reflect on this entire unit as a whole, it definitely has not been as hard as I imagined it would be. I thought there would be very difficult calculations and the concepts would be extremely hard. So far, I've gotten down the calculations fairly easily, and although the conceptual stuff is pretty difficult, I am definitely starting to get it more.
